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Understanding the European Avalanche Danger Scale
The European Avalanche Danger Scale runs from 1 (Low) to 5 (Very High). It is the foundation of every avalanche bulletin published by services like the SLF in Switzerland, the state Lawinenwarndienste in Austria and avalanche.report for Tyrol, and Météo-France.
Level 1 (Low): Generally stable snowpack. Natural avalanches unlikely. Human-triggered avalanches possible only on very steep, extreme terrain.
Level 2 (Moderate): The snowpack is only moderately well bonded on some steep slopes; elsewhere it is generally well bonded. Human-triggered avalanches possible on steep slopes with the characteristics described in the bulletin.
Level 3 (Considerable): The snowpack is critical on many steep slopes. Human-triggered avalanches are likely. Natural avalanches are possible.
Level 4 (High): The snowpack is poorly bonded on most steep slopes. Human-triggered avalanches are likely on many steep slopes, even from a single skier or snowboarder. In some cases, many large and often very large natural avalanches are expected.
Level 5 (Very High): Extremely unstable snowpack. Numerous large natural avalanches expected. Avoid all avalanche terrain.
In Switzerland about half of avalanche deaths happen at level 3 (SLF): dangerous enough to kill, and many people still go. At level 3, staying away from steep terrain (above 30 degrees) with the aspect and elevation described in the bulletin is essential. For a detailed breakdown of how to interpret every part of the bulletin, read our guide on how to read an avalanche bulletin.
Five things to check on a slope
Five things decide most of the avalanche question on a slope: how steep it is, where it sits, which way it faces, what is underneath the snow and its shape. This checklist is not the same as SLABS, the 2024 risk model from Skitourenguru, SLF, VITO and NTNU, which BEYOND runs for an area with the bulletin as input.
Slope angle
Most slab avalanches release on slopes between 30 and 45 degrees. Slopes under 30° are below the typical release angle; what reaches them is the runout of steeper slopes above. Slopes over 50 degrees tend to shed snow continuously rather than building dangerous slabs.
A slope angle overlay (like the one available in BEYOND) lets you identify which parts of a mountain fall in the critical 30-45 degree range before you commit to a line. The layer shows the angle, not today's snowpack: whether a 35° slope is a problem today is in the bulletin.
Location: Elevation and Geography
The avalanche bulletin specifies which elevation bands are most dangerous. Wind-loaded slopes near ridgelines are typically more hazardous than sheltered forest terrain. Gullies and terrain traps below steep slopes increase consequences even on lower-angle terrain.
Aspect: Which Direction the Slope Faces
The bulletin names the critical aspects when there are any; check your line against them at the named elevations.
Base: What is Underneath
Smooth ground surfaces like grass or rock slabs provide less anchoring for the snowpack. Slopes with a smooth base are more likely to produce full-depth avalanches. Rough terrain with boulders and trees provides better anchoring, though trees alone do not guarantee safety.
Shape: Terrain Features
Convex slopes (where the terrain rolls over from flatter to steeper) concentrate stress in the snowpack and are common trigger points. Concave slopes distribute stress more evenly but can collect wind-deposited snow. Terrain traps like cliffs, gullies, and crevasses below a slope increase the consequences of even a small avalanche.
Essential Safety Gear
Every person carries an avalanche transceiver, a probe and a shovel, and knows how to use them. Practise companion rescue regularly.
In Haegeli et al. (2014) an inflated airbag halved mortality, 22% to 11%; one in five was not inflated. What to look for in each item is in backcountry gear for ski touring.
Making Better Decisions
Fatigue, peer pressure, summit fever and familiarity bias push riders into terrain they would otherwise keep off.
Plan your route before you leave. Check the avalanche bulletin. Identify your turnaround points and tell the group.
Tools like BEYOND help you evaluate terrain before you are standing in it, when the pressure to commit is highest. Look at the 3D terrain, look at slope angles, check the bulletin, and see where the terrain is steeper than 30 degrees from home.